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Regarding Sprinkler Protection in Elevator Shafts
According to 2010 NFPA 13, section 8.15.5, fire sprinkler protection is required at the top and bottom of elevator shafts. There are exceptions noted in that section, but when sprinkler heads are installed in elevator shafts, then they must also be installed according to the State adopted Elevator Code. This "Elevator Code" has a section which has to do with the electrical and piping hookup in elevator hoistways and machine rooms. It states that the main line power must be automatically disconnected before or upon water being released, and that this must not be achieved by smoke detectors, or by fire sprinklers outside of the hoistway/machine room. If there is no head at the top of the shaft, and if the head at the bottom of the shaft is within 2 feet of the bottom, then the main line power may remain on. If the power is required to be shut off, then NFPA 13, (2010) A.22.214.171.124 tells you how to achieve this requirement.
There are three common methods used to meet this automatic main line power disconnect before water is released.
One way, which is typically the most economical way, is with a fire sprinkler system flow switch that does not have a time delay. In a fire, the flow switch would activate not only an alarm, but it would also cause a shunt trip breaker to disconnect the main line power to the affected elevator upon activation of the fire sprinkler.
Another way is with the use of a rate-of-rise/fixed temperature heat detector. These detectors would be placed near each fire sprinkler and the fire sprinkler heat rating would exceed the heat detector ratings. The detectors would be independent of the sprinkler system. In a fire, the heat detector would trip first and cause a shunt trip breaker to disconnect the main line power to the affected elevator before activation of the fire sprinkler.
A third way is with a pre-action sprinkler system. Pre-action systems have a supplemental fire detection system installed in the same area as the sprinklers. These would be heat detectors. Actuation of a heat detector from a fire would trip a valve, which would release water to fill the pipe. Water would not be released from the pipe though until a sprinkler head fused from additional heat. Either the heat detector, or the flow switch in the sprinkler piping would cause a shunt trip circuit breaker to disconnect the main line power to the affected elevator at the time the valve is tripped and water flows into the sprinkler piping.
Regardless of which method is used, smoke detectors are not allowed in place of the heat detectors for the purpose of main line power disconnect, as stated in Rule 102.2 © (4) of ASME A17.1 (1996) Safety Code for Elevators & Escalators. Smoke detectors are used inside/outside of the hoistway to do what is called a Phase 1 recall of the elevator to a predetermined building level for use for firefighter's service. These smoke detectors do not disconnect the main line power, because the firemen may need it.
In harmony with the intent of the elevator code to minimize water in the elevator shaft, our office requires a shutoff valve outside of the elevator shaft for each fire sprinkler head within the shaft. The shutoff valve needs to be located in such a way as to minimize the quantity of water drained into the shaft area when servicing that fire sprinkler head in the shaft. A similar shutoff valve is required for elevator mechanical rooms when the functioning of the equipment in those rooms is seriously threatened by large quantities of water from draining a fire sprinkler system. The same shutoff valve can be used for both rooms. The reason for minimizing the amount of water in these areas is to minimize the chance of brake failure or electrocution.
The Elevator Code also states that all risers and returns shall be located outside of the hoistway/machine room, and that branch lines in the hoistway shall supply sprinklers at not more than one floor level. For more information on the Elevator Code, call Stan Quinn at 207-624-8675 or John Burpee at 207-624-8546.
[Last Updated 1-11-12 to reflect currently adopted codes and standards with their references.]
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